Abstract

In Korean herbal medicine dandelion (Taraxacum officinale, TO) has been used to improve energy levels and health. However, the effects of TO in experimental models remain unclear. We examined the anti-fatigue and immune-enhancing effects of TO in mice by performing a forced swimming test (FST) and in vitro by using peritoneal macrophages, respectively. After daily oral administration of TO, blood biochemical parameters related to fatigue were measured after the FST. FST immobility time was significantly decreased in the TO-treated group (100 mg/kg) on the tenth day. TO (10 and 100 mg/kg) treatment significantly increased glucose levels, acting as an energy source. The level of lactic dehydrogenase, which is an accurate indicator of muscle damage, tended to decline after TO administration (10 and 100 mg/kg). When TO (100 mg/kg) was orally administered to mice, blood urea nitrogen levels decreased significantly. We also examined the effect of TO on the production of cytokines and nitric oxide (NO) in mouse peritoneal macrophages. When TO was used in combination with recombinant interferon-gamma (rIFN-&#947;), a noticeable cooperative induction of tumor necrosis factor-alpha (TNF-&#945;), interleukin (IL)-12p70, and IL-10 production was observed. Furthermore, in peritoneal macrophages, rIFN-&#947; plus TO treatment significantly increased the production of NO through inducible nitric oxide synthase (iNOS) induction. Taken together, these results suggest that TO improves fatigue-related indicators and immunological parameters in mice.

Effect of TO on immobility time in mice. One day after the first measurement of immobility, the administration of TO (10 and 100 mg/kg/day, p.o.) was started; this continued for a total of 10 days. Three days after the first administration, the second measurement of immobility was made. After the last administration (the 10th day), the third measurement of immobility was made. Values are the mean ± S.E. of twice experiments (n = 10). *p < 0.05 vs. distilled water-treated group.

Effects of TO on rIFN-γ plus TO-induced TNF-α and IL-12p70 productions and mRNA expressions in peritoneal macrophages. (A) Peritoneal macrophages (3 × 105 cells/well) were incubated for 1 h with rIFN-γ (10 U/mL). The peritoneal macrophages were then stimulated with TO (0.01–1 mg/mL) for 24 h. The supernatants were analyzed for cytokines expression by ELISA as described in the method. (B) Peritoneal macrophages (3 × 105 cells/well) were incubated for 1 h with rIFN-γ (10 U/mL). The peritoneal macrophages were then stimulated with TO (0.01–1 mg/mL) for 6 h. Total RNA was prepared for real time RT-PCR analysis TNF-α and IL-12p70 expressions in peritoneal macrophages. The experiment was repeated three times and similar results were obtained. Values represent means ± S.E. of three independent experiments. *p < 0.05 vs. rIFN-γ (10 U/mL); **p < 0.01 vs. rIFN-γ (10 U/mL) significant differences between treated groups were determined by ANOVA and Dunnett’s post-hoc test.

Effects of TO on rIFN-γ plus TO-induced IL-10 productions in peritoneal macrophages. Peritoneal macrophages (3 × 105 cells/well) were incubated for 1 h with rIFN-γ (10 U/mL). The peritoneal macrophages were then stimulated with TO (0.01–1 mg/mL) for 24 h. The supernatants were analyzed for cytokines expression by ELISA as described in the method. The experiment was repeated three times and similar results were obtained. Values represent means ± S.E. of three independent experiments. *p < 0.05 vs. rIFN-γ (10 U/mL); ***p < 0.01 vs. rIFN-γ (10 U/mL) significant differences between treated groups were determined by ANOVA and Dunnett’s post-hoc test.

Effects of TO on NO productions, protein, and mRNA expressions in peritoneal macrophages. A) Peritoneal macrophages (3 × 105 cells/well) were incubated for 1 h with rIFN-γ (10 U/mL). The peritoneal macrophages were then stimulated with TO (0.01–1 mg/mL) for 48 h. The supernatants were analyzed for NO production by Griess method as described in the method. B) Cells were pretreated with different concentrations (0.01–1 mg/mL) of TO for 12 h. Total cellular proteins (40 μg) were resolved by SDS-PAGE, transferred to nitrocellulose membranes, and detected with specific antibodies, as described in Materials and Methods. A representative immunoblot of three separate experiments is shown. C) Total RNA was prepared for real time RT-PCR analysis iNOS expressions in peritoneal macrophages. The experiment was repeated three times and similar results were obtained. Values represent means ± S.E. of three independent experiments. *p < 0.05 vs. rIFN-γ (10 U/mL); **p < 0.01 vs. rIFN-γ (10 U/mL) significant differences between treated groups were determined by ANOVA and Dunnett’s post-hoc test.